Richard M. Nixon’s fate was effectively sealed 40 years ago today. It’s a curious coincidence at the start of an August recess when the extraordinarily serious matter of presidential impeachment is going to be tossed around in such a cavalier and cynical manner.

In the current era of partisan gamesmanship and governmental gridlock, it’s understandably difficult to comprehend what a genuine constitutional crisis feels like. But there is no doubt that’s what steadily swelled toward its climax on Aug. 5, 1974.

That Monday afternoon, Nixon made public transcripts of three conversations he’d had with White House Chief of Staff H.R. Haldeman just six days after the June 1972 break-in at Democratic Party headquarters in the Watergate complex. The move ended parallel standoffs — between the president and Congress and between the president and federal prosecutors — that had festered for two weeks, even after the Supreme Court ruled 8-0 that Nixon could not claim executive privilege and had to fork over the records subpoenaed for the Watergate cover-up trial. The House Judiciary Committee had also been stiff-armed after issuing similar subpoenas on the way to approving its three articles of impeachment, with solid bipartisan support, in July.

Beyond breaking the separation-of-powers fever, the transcripts provided all the evidence necessary to bring Nixon’s presidency to a dramatically swift end. His words, preserved on what came to be known as the “smoking gun” tape, left no doubt he had personally launched a criminal conspiracy. The president had effectively ordered the cover-up of the Watergate burglary, agreeing that top CIA officials should be instructed to pressure the FBI to halt its investigation of the crime on cooked-up “national security” grounds.

Within hours, Nixon’s tenuous wall of congressional support crumbled. All 10 Republicans who had voted against impeachment in committee said they would vote on the floor for at least the article alleging obstruction of justice. (The other charges were abuse of presidential power and contempt of Congress.) Senior Republican senators were dispatched to inform the president he could not count on more than 15 votes for acquittal at a Senate trial. Nixon chose instead to resign, announcing that decision Thursday night and leaving office the morning of Friday, Aug. 9.

The anxiety of that sustained constitutional impasse — capped by a president who had proclaimed “I am not a crook” quitting after being forced to reveal he really was one — is seared in the memories of everyone on the Hill who lived through it. (The most recent reminder was the July 29 death , at age 89, of former Rep. Caldwell Butler of Virginia, who as a freshman on Judiciary conceded he broke down and wept after becoming among the first committee Republican to announce support for impeachment.)

But Watergate also was the formative national trauma for anyone who arrived in Congress from the 1970s through the 1990s, the generations who still hold sway over the national debate. For those politicians, regardless of ideology, Nixon’s forced resignation ranks with the Sept. 11, 2001, terrorist attacks and the assassination of President John F. Kennedy as the dates in their lives that most live in infamy.

The desire to prevent a repeat of the Nixon drama helped prompt Democrats, just 12 years later, to quickly quash calls for President Ronald Reagan’s impeachment, despite solid evidence he violated the law and misled Congress in the Iran-Contra affair. Similar sentiment fueled the Senate’s never-in-doubt, bipartisan 1999 acquittal of President Bill Clinton on the House GOP’s charges that he should lose his job for lying to a grand jury and otherwise trying to cover up his affair with West Wing intern Monica Lewinsky. A decade later, Democrats made clear they had no interest in spending the final years of George W. Bush's presidency prosecuting him for launching the Iraq War under suspect pretenses.

In that context, this summer’s casual talk sounds astonishing. Both sides are equally aware that President Barack Obama is not going to be impeached during the 113th Congress. There are not anywhere close to enough votes. Unsurprisingly, not one of his fellow Democrats has given a whiff of credence to the notion that the president has committed any “high crimes and misdemeanors,” the vague phrase in the Constitution that assures the standard for removal from office is inherently political, not legal.

More importantly, by the time the recess started last week, no more than 15 House Republicans (or 6 percent) had outwardly expressed any sort of appetite for the move. Dozens more may be keeping their enthusiasm to themselves, but even all their support would leave the House Republican Conference deeply divided. And it takes 93 percent support from the GOP to see anything through on a party-line ballot. That math helped prompt Speaker John A. Boehner into concocting his alternative — the House’s vote last week to file a long-shot lawsuit alleging Obama overstepped his presidential powers in the way he’s implemented the 2010 health care law.

So why does the impeachment chatter persist? Because there are camps in both parties that believe of the specter of ousting Obama brings short-term tactical benefits to their side.

Plenty of Republicans don’t believe in the substantive virtues of the idea . They are aware the public is 2-to-1 opposed and that the Clinton impeachment backfired on them politically. They know the Democratic Senate has zero interest in putting the president on trial, and they understand that having Joseph R. Biden Jr. as president wouldn’t make the White House any more centrist in any event. But conservative occupants of safe seats are nonetheless convinced that keeping the threat of impeachment alive will help them boost both their fundraising and their base vote.

On this, they are in a weird sort of agreement with the White House and top Democrats. The president and his party are confident that pumping up talk about the lawsuit being the first step toward impeachment will benefit their campaign coffers and their turnout.

Initial indications are the Democrats are getting a bit more out of their version of the same baseless rhetoric. Early estimates are that, in the week before the lawsuit vote, online appeals from candidates and campaign committees that mentioned impeachment raised about $5 million in mostly small-money donations.

Cooking up worries about a non-existent constitutional crisis just to rake in campaign cash, well, such a jaded ploy might have made Caldwell Butler cry again. It might even have made Nixon blush.